CN102459835B - Exhaust line with injection system - Google Patents

Abstract

The invention relates to an exhaust line for a motor vehicle, comprising: -two upstream (14) and downstream (16) blocks for treating the exhaust gases flowing in the exhaust line (2), said upstream (14) and downstream (16) blocks being arranged in succession in the exhaust line (2); an injection portion (18) disposed between an upstream face (20) defined by the upstream block (14) and a downstream face (22) defined by the downstream block (16), including a flow-through passage (24) disposed for exhaust gas flow extending from the upstream face (20) to the downstream face (22), the passage (24) including a centerline (L1) of a determined length between the upstream face (20) and the downstream face (22), the injection portion (18) including a reactant injector (26) mounted on the injection portion (18) and configured to inject a reactant into the injection portion. The injection portion (18) includes at least a first cup (30) disposed within the flow channel (24) in the exhaust flow path such that an average path of the exhaust jet is at least 20% higher than the predetermined length.

Description

Exhaust line with injection system

technical field

The present invention generally relates to automotive exhaust lines having reductant injection means for selective reduction catalysts of engine exhaust gases.

Background technique

More specifically, the present invention relates to the use of automotive exhaust lines of the type comprising:

Two upstream and downstream blocks are used to treat the exhaust gas flowing in the exhaust pipeline, and the upstream and downstream two blocks are arranged in series in the exhaust pipeline;

an injection section, disposed between an upstream face bounded by said upstream block and a downstream face bounded by said downstream block, comprising: a flow channel for exhaust gas flow extending from said upstream face to said downstream face , the channel includes a centerline having a determined length between the upstream face and the downstream face, the injection portion includes a reactant injector mounted on the injection portion and capable of injecting reactants into the injection portion.

Such an exhaust line is used to equip an internal combustion engine, such as a diesel engine, comprising a system for reducing nitrogen oxides and an injector for a reducing agent, such as urea, upstream of the system. The most common configuration of the urea injection section is generally located between the upstream particulate filter (after the oxidation catalyst) and the downstream selective catalytic reduction system (SCR) of nitrogen oxides. Another rather common solution consists in placing the injection part between the oxidation catalyst and an impregnated particulate filter dealing with the reduction of nitrogen oxides or between the oxidation catalyst and an SCR catalyst preceding a conventional particulate filter.

However, in both cases, from the outlet face of the upstream block (particulate filter or oxidation catalyst) all the way to the next block (SCR catalyst, or impregnated particulate filter or SCR in front of the standard particulate filter) The inlet face of the catalytic converter), the injection portion comprising: a converging cone reducing the diameter of the gas passage, a pipe supporting the injector, and a diverging cone increasing the diameter of the gas passage. Furthermore, in most cases the injection section comprises a mixer located within the duct supporting the injector.

This setup constitutes an incompressible link, especially due to the presence of converging and diverging cones. In addition, in order to ensure the correct operation of the urea injection system, it is necessary to ensure the functions of injecting urea, volatilization, hydrolysis-pyrolysis into ammonia gas and mixing ammonia gas with exhaust gas so that the ammonia gas in the exhaust gas at the intake face of the downstream block very evenly distributed. This conversion of urea to ammonia and the mixing between ammonia and exhaust gas takes time and therefore requires very long path distances.

Overall, the distance between the two blocks was reduced to 200mm by optimizing the different functions as much as possible. However, this reduced distance arrangement is fragile and expensive to manufacture.

Contents of the invention

In this context, the object of the invention is to provide an exhaust line that functions more satisfactorily, is less bulky and is less expensive to manufacture.

To this end, the invention relates to an exhaust gas line of the aforementioned type, characterized in that the injection part comprises at least a first cup arranged in a flow channel in the flow path of the exhaust gas so that the exhaust gas jet The average path is at least 20% higher than the predetermined length.

Considered individually, or in accordance with all technically feasible combinations, the exhaust line may comprise one or more of the following features,

- said defined length is substantially between 40 and 140 mm;

- the bottom of the first cup helically surrounds the center line of the injection part;

- the bottom of the first cup rotates three-quarters of a revolution around the center line of the injection part in a helical shape;

- said first cup has an opening at the end of said helix farthest from said upstream face;

- said first cup has a spoiler at the end of said helix farthest from said upstream face;

- said spoiler extends from the bottom of said first cup towards said upstream face and towards the outer portion of said helix;

- said injection portion comprises a second cup disposed in a flow channel between said upstream face and said first cup, the second cup having a bottom helically surrounding the centerline of said injection portion ;

- said second cup has an opening at the end of said helix farthest from said upstream face;

- said second cup has an opening at the end of said helix closest to said upstream face;

- said two cups define between them a helical duct starting from the opening of said second cup and leading to the opening of said first cup extending at least 180°, preferably, stretching 275°, with a flat area substantially greater than ^2300mm2 ;

- said first cup comprises: an annular wall having a central area protruding towards said upstream face and a hollow peripheral area surrounding said protruding central area towards said upstream face; an opening formed in on the wall of the first cup between the protruding central region and the hollow peripheral region;

- said injection portion comprises a second cup disposed in a flow channel between said upstream face and said first cup, said second cup comprising: an annular wall with a direction towards said upstream a hollow central region of a face and a peripheral region protruding toward said upstream face surrounding said hollow central region; and an opening formed in said second cup between said hollow central region and said protruding peripheral region on the wall of the body;

- said first and second cups are shaped such that exhaust gases undergo a spiral movement from the opening of said second cup to the opening of said first cup;

- injecting reactants between said first cup and said second cup;

- the opening of said first cup and the opening of said second cup are angularly offset from each other about said centreline;

- said cup has a hole or opening with a diameter substantially equal to 5 mm;

- said first cup comprises a wire mesh layer on at least a part of its surface;

- said reactant injector is oriented such that the direction of injection is perpendicular to said injection portion; and

- said reactant injectors are oriented so that the injection direction is parallel to the tangential plane of said injection portion.

Description of drawings

Other characteristics and advantages of the invention will emerge from the detailed description with reference to the accompanying drawings, in which,

1 is an exploded perspective view of an exhaust pipeline according to an embodiment of the present invention;

Figure 2 is an exploded perspective view of the exhaust line of Figure 1, depicting the operation of the exhaust line;

Fig. 3 is a combined perspective view of the exhaust pipeline of Fig. 1;

Figures 4, 5, 6 and 7 are schematic views of the exhaust line of Figure 1 with means for homogenizing the gas/urea mixture;

8 is a cross-sectional view of a second embodiment of an exhaust pipeline according to the present invention;

Fig. 9 is a perspective view of the cup in the second embodiment of the exhaust pipeline of Fig. 8;

Fig. 10 is a perspective view of a cup in the second embodiment of the exhaust pipeline of Fig. 8;

11 is a cross-sectional view of a third embodiment of an exhaust pipeline according to the present invention;

12 is another cross-sectional view of a third embodiment of the exhaust line of FIG. 11; and

FIG. 13 is a perspective view of the cup in the third embodiment of the exhaust pipeline of FIG. 11 .

Detailed ways

In the following description, upstream and downstream are to be understood relative to the normal flow direction of the exhaust gas through the exhaust line, indicated by the arrows in the figures.

FIG. 1 partially shows an exhaust gas line 2 installed in a motor vehicle equipped with an internal combustion engine, for example a diesel engine. The exhaust gas line 2 includes two exhaust gas treatment devices 4 , 6 . Each exhaust gas treatment device 4 , 6 comprises a housing 10 , 12 and a block 14 , 16 disposed within the housing 10 , 12 .

For example, the upstream exhaust gas treatment device 14 is a particle filter or an oxidation catalyst and the downstream exhaust gas treatment device 16 is an SCR catalyst, or an SCR impregnated particle filter or an SCR catalyst followed by a standard particle filter.

The block of an oxidation catalyst or SCR comprises, for example, a gas-permeable structure covered with a catalytic metal which facilitates the oxidation of combustion gases and/or the reduction of nitrogen oxides. The block of the particulate filter is used to contain the soot emitted by the engine and also to trap gaseous pollutants.

The exhaust line 2 also includes an injection portion 18 arranged between an upstream face 20 delimited by the upstream block 14 and a downstream face 22 delimited by the downstream block 16 . The upstream face 20 is the face through which the exhaust gas leaves the upstream block 14 , and the downstream face 22 is the face through which the exhaust gas enters the downstream block 16 .

Said injection part 18 comprises a flow channel 24 extending from said upstream face 20 to said downstream face 22 for the flow of exhaust gas and a valve mounted on said injection part 18 and capable of injecting reactants into said injection part 18. Reactant injector 26 .

Said channel 24 has a centerline L1 having a definite length between said upstream face 20 and said downstream face 22 . The center line L1 is a line passing through the geometric center of the rectilinear region of the flow channel 24 . In the example shown, this center line L1 is a straight line parallel to the axes of said upstream and downstream blocks, perpendicular to said upstream face 20 and said downstream face 22 and passing through their centres.

The injection portion 18 comprises a cup 28 which is arranged in the flow channel 24 in the flow path of the exhaust gas. This cup 28 is called a weir. The base of this weir 28 is in a spiral around the center line of the injection section, with a large opening 29 at the end of the spiral furthest from the upstream face. The opening 29 is inclined relative to the center line L1 and to a plane perpendicular to the center line L1.

The diameter of the cup body 28 is equal to the inner diameter of the exhaust gas flow channel, which extends over the entire linear region of the flow channel 24 . The peripheral edge of the cup 28 supports the inner surface of the flow channel.

The helical shape of the weir 28 imparts a swirling motion to the exhaust gases with the only holes downstream. The exhaust gas approximately completes one full revolution.

The uppermost portion of the weir 28 is approximately 6 mm from the outlet face 20 of the upstream block. According to another embodiment, this distance may be increased to 10 mm in order not to increase the back pressure excessively.

Furthermore, said injection portion 18 comprises a second cup 30 , called “channel”, arranged in said flow channel 24 between said first cup 28 and said downstream face 22 , said second cup The body 30 has a bottom that spirally surrounds the center line L1 of the injection portion.

Preferably, the bottom of the second cup body 30 revolves around the central line L1 of the injection part in a helical shape for three quarters of a rotation.

Said second cup 30 has an opening at the end of said helix furthest from said upstream face. The opening is defined by both end edges of the helical bottom of the second cup body 30 and the walls of the flow channel 24 .

The diameter of the cup body 30 is equal to the inner diameter of the exhaust gas flow channel, and it extends in the entire linear region of the flow channel 24 , and the peripheral edge of the cup body 30 supports the inner surface of the flow channel.

Said two cups 28, 30 define between them a helical duct leading from the opening 29 of said weir 28 to the opening of said cup 30, extending at least 180°, preferably , extending 275°. This helical duct is laterally bounded by the inner surface of said flow channel 24 .

The helical duct in the opening of the cup provides an area for the exhaust gases of substantially greater than 2300 mm ² , preferably at least 2375 mm ² . This area corresponds to a pipe area with a diameter of 55 mm, which is usually used in the exhaust line, especially in the injection part.

The openings of the first cup 28 and the second cup 30 are angularly offset from each other about the centerline L1 to avoid any direct path parallel to the centerline L1 of the exhaust gas flow injection portion.

The injection portion has a cylindrical side wall with a diameter of about 150 mm, substantially equal to the diameter of the gas treatment device, and a length of the side wall between 40 mm and 140 mm. Preferably, the distance between the upstream face of the upstream block and the downstream face of the downstream block is between 60 mm and 100 mm.

Said side walls are made in a single piece, the casing 12 of which surrounds the downstream block 16 .

For example, the two cups are fixed to the side walls by welding.

Said side wall comprises an orifice for introducing and securing an injector of reactant, here urea, to the wall located between the first cup 28 and the second cup 30 . The injector is oriented such that the injection direction is perpendicular to the sidewall.

According to an alternative, said injector is oriented such that the direction of injection is at an angle of 40° to 45° relative to the tangent of said side wall, so that the ejection flow is in line with the direction of the exhaust gas.

According to another alternative, depicted with dotted lines in FIG. 3 , said injector 26 is oriented so that the injection direction is parallel to the tangent plane of said side wall, so that a more compact injection portion 18 can be obtained.

According to another alternative, said first cup 28 comprises a local deflector preventing the jet of urea droplets from coming into contact with said upstream block 14 . For example, the partial deflector is formed by cutting out said first cup.

The operation of the exhaust line described above will now be described in detail with reference to Figure 2, which depicts the exhaust gas jet.

After passing through the upstream block 14, the exhaust gas leaves the upstream block 14 in a substantially uniform distribution state. The exhaust gas flow is laminar and generally parallel to the centerline L1. The exhaust gas reaches the first cup body 28 . The first cup 28 blocks the gas flow parallel to the central line L1, and the helical shape of the first cup 28 causes the gas to perform a rotational movement.

Next, the gas enters said channel 30, the helical shape of which maintains the rotational movement of the gas.

At the outlet of the first cup 28 or weir, urea is injected into the upstream part of the channel 30 . The conversion of urea to ammonia occurs during the passage of the gas through the channel 30, ie the time required for the gas to rotate three quarters of the way. During this three-quarter revolution, the average distance traveled by the exhaust gas is about 180 mm. This distance corresponds to the distance required to convert urea into ammonia using an injector with a jet having a mean diameter (SMD) of 90 μm, an injection velocity of 25 ms and a scattering angle of 16°.

Once the gas reaches the opening or outlet of said channel 30 it passes through said downstream block 16 .

The gas that has reached this stage has, on average, performed slightly more than one revolution; thus the gas acquires a significant tangential velocity and "attacks" the downstream face 22 or the next block 16 with this gas component. entrance face. It is known that reaching the block in this way facilitates a good, uniform distribution over the block.

Typically, said injection portion 18 has a length of only 60 mm and a diameter of 150 mm, ie the diameter of the shell surrounding said upstream and downstream blocks. In this way, as shown in FIG. 3 , the injection portion is contained in a cylinder of 60 mm x 150 mm (diameter) and enables the mean path of the exhaust gas jet relative to a defined length between the upstream face 20 and the downstream face 22 20% increase.

Furthermore, if the gas flow rate is different than the previous example, then the length of the cylinder will be different to create the desired flow area. If the flow rate is higher, the distance between the two blocks must be increased. If the flow rate is low, then the distance between the two blocks is reduced.

This embodiment can be used in horizontal or vertical sections under the car floor or end shell (in closed position).

Of course, the system can use all types of urea injectors, these different injectors being characterized by a wide range of jet streams. These jets have wider or narrower columns, different mean diameters for very fine droplets or relatively large droplets, and greater or lesser jet velocities.

Therefore, in order to ensure optimum homogeneity, said first cup 28 has a hole 40 with a diameter substantially equal to 5 mm, as shown in FIG. 4 .

For example, if the jet of the injector 26 contains fine droplets of low energy, the urea droplets will not be able to penetrate deeply into the gas jet. The urea concentration on the outer edges of the channel 30 will therefore be greater than the urea concentration in its centre. The holes 40 of the weir 28 above the outer edge of the channel 30 allow the gas leaving the upstream block 14 to pass to the inlet of the channel 30 and reduce the urea/air ratio at the periphery of the channel 30 .

Conversely, if the injector 26 is characterized by a central portion within the channel 30 where most of the urea is located, the hole 40 overhangs this area.

According to an alternative depicted in FIGS. 5 and 6 , said injection part 18 comprises a linear mixer located between said two cups to create an obstruction with the purpose of intercepting the flow in order to homogenize the exhaust gases and urea or ammonia gas. The form of the mixer can be installed on the second cup body 30 shown in FIG. 5 and towards the fins 50 or fins shown in FIG. The spiral shape 60.

According to another alternative shown in FIG. 7 , the second cup body 30 comprises a wire mesh layer 70 arranged on at least a part of the surface of the second cup body 30 . Before assembling, the second cup body 30 is provided independently of other parts constituting the injection part 18, so that the silk mesh layer 70 can be placed where it is necessary to volatilize urea and convert urea to ammonia. optimized position. In practice, it is very difficult to place said mesh layer 70 in the exhaust pipe. In a known manner, the addition of the screen layer 70 makes it possible to increase the contact surface between urea and exhaust gas by considerably increasing the metal/gas exchange surface.

In FIG. 7 , the part of the channel 30 covered by the wire mesh 70 is hotter than the outer wall; there, the volatilization of urea and the conversion of urea to ammonia are therefore easier and faster.

The wire mesh layer 70 can also be placed on the lower part of the first cup body 28 (not shown here) opposite to the second cup body 30 .

Considered individually, or in accordance with all technically feasible combinations, said injection portion 18 may comprise one or more of these alternatives in order to obtain an optimum homogeneity of the gas/ammonia mixture.

A second embodiment of the injection portion 318 is depicted in Figures 8 (sectional view), 9 and 10 (perspective views). The injection portion 318 includes a first cup 328 and a second cup 330 .

The housing 12 of the downstream exhaust gas treatment device 6 is fixed at the lower part of the housing 10 of the upstream exhaust gas treatment device 4 to seal the exhaust gas. The downstream block 16 and the two cups 328 , 330 are within the downstream housing 12 .

The first cup 328 has a bottom that surrounds the injection part 318 in a spiral shape. The first cup 328 has a concave surface towards the downstream face 22 such that the bottom of the first cup 328 forms a cover for the second cup 330 .

The first cup 328 has a large opening 329 at the end of the helix closest to the upstream face 20 . The opening 329 is inclined relative to the centerline L1 and a plane perpendicular to the centerline L1.

The first cup 328 has a peripheral edge 350 extending from the bottom of the first cup 328 and extending generally perpendicular to the centerline L1 , the peripheral edge 350 passing through a peripheral cavity 352 formed in the upstream portion of the downstream housing 12 . The outer periphery 350 of the first cup 328 is fixed at the downstream housing 12 to seal against exhaust gases, for example by welding.

The bottom of the first cup 328 also includes holes 340 to ensure optimal uniformity of the exhaust gas.

The second cup body 330 is disposed between the first cup body 328 and the downstream face 22 , and the second cup body 330 has a bottom that spirally surrounds the center line L1 of the injection portion 318 .

Preferably, the bottom of the second cup 330 revolves at least three quarters around the central line L1 of the injection part 318 in a spiral shape.

The second cup 330 has an opening 354 at the end of the helix furthest from the upstream face 20 . The opening 354 is defined by the two end edges 356A, 356B of the spiral bottom of the second cup 330 and the peripheral wall 358 of the second cup 330 which supports the the inner surface of the flow channel.

The second cup 330 has a peripheral edge 360 extending from the peripheral wall 358 of the second cup 330 and extending generally perpendicular to the centerline L1, the peripheral edge 360 passing through a peripheral cavity formed in the upstream portion of the downstream housing 12 352. The peripheral edge 360 of the second cup 330 is fixed at the downstream housing 12 to seal the exhaust gas, for example by welding.

Therefore, the peripheral edge 350 of the first cup 328 and the peripheral edge 360 of the second cup 330 are disposed opposite to each other, contact each other, and are fixed to each other to seal the exhaust gas, for example by welding.

The two cups 328, 330 define between them a helical duct extending from the opening 329 of the first cup 328 to the opening 354 of the second cup 330 and extending At least 180°, preferably, a stretch of 275°.

The second cup 330 also includes a spoiler 380 arranged at the downstream end of the second cup 330 , ie at the end of the helix farthest from the upstream face 20 . The spoiler 380 extends from the bottom of the second cup 330 towards the upstream face 20 and the outside of the helical duct and is defined by an end edge 356B. The spoiler 380 thus forms a slotted opening towards said upstream face 20 .

As an example, the spoiler 380 has a curve radius of 5.5 mm and a height of 7 mm, which can be increased to 10 mm in height. The spoiler 380 extends angularly over 10°, which value can be increased to 90°.

As will be explained in more detail below, the spoiler 380 is capable of limiting the ammonia concentration immediately after the opening 354 .

The present invention provides a reactant injector (not shown) for injecting into the helical conduit defined by the two cups 328,330. For this purpose, the reactant injector is installed at the bottom of the first cup 328 , close to the opening 329 .

According to an alternative, the injector is mounted on the peripheral wall 358 of the second cup 330 .

The operation of the exhaust line according to the second embodiment described above will now be described in detail with reference to FIG. 8 , which shows the exhaust gas flow with arrows.

As mentioned above, the exhaust gas reaches the first cup 328 . The gas is collected by the first cup 328 after passing through the upstream block 14 .

The exhaust gas then passes through the helical duct through the opening 329 or through the hole 340 and flows in the helical duct upwardly to the opening 354 .

Urea is injected at the inlet of the helix and is converted to ammonia as the exhaust gas passes through the helix.

At the exit of the helical duct, the spoiler 380 forces the lower layer of the exhaust gas, i.e., the gas layer near the second cup 330 with a large amount of ammonia, to suddenly change direction upwards, i.e., Towards the upstream face 20 and mixed with the layer of gas directly above it, this intermediate layer carries less ammonia. The exhaust gas at the outlet of the second cup body 330 has an average and uniform ammonia gas concentration.

In addition, the spoiler 380 deflects the lower layer of gas abruptly, creating a vacuum right at the outlet of the second cup 330 in the area indicated by reference numeral D in FIG. 8 . This vacuum sucks the exhaust gas between the outlet of the second cup 330 and the downstream block 16 , resulting in a better rotation of the exhaust gas on said downstream face 22 .

As an example, where the injection portion 318 has a diameter of 150 mm and a length of 70 mm, the ammonia homogeneity index on the downstream face 22 may be increased by five to nine percent.

Furthermore, as in the previous case, the mixer is integrated in the helical duct and/or part of the walls of this helical duct may contain wire mesh to guarantee an optimal homogeneity of the gas and urea and/or ammonia.

The advantage of this embodiment is that the distribution of the ammonia gas on the downstream face 22 of said downstream block 16 is improved, so that the ammonia gas is evenly distributed in the downstream block 16 .

A third embodiment of the injection portion 418 is depicted in FIGS. 11 , 12 (sectional view) and 13 (perspective view). The injection portion 418 includes a first cup 428 and a second cup 430 .

Via the second cup 430 , the housing 12 of the downstream exhaust gas treatment device 6 is fixed at the housing 10 of the upstream exhaust gas treatment device 4 to seal the exhaust gas. The two cups 428 , 430 are disposed at the junction between the upstream housing 10 and the downstream housing 12 , the first cup 428 is inside the upstream housing 10 and the second cup 430 is inside the downstream housing 12 .

The first cup 428 is open towards the downstream face 22 and comprises an annular wall without sharp edges. This wall has a hollow central area 450 facing said upstream face 20 and a peripheral area 452 protruding towards said upstream face 20 surrounding said hollow central area 450 . The raised peripheral region 452 includes a lower peripheral portion 454 and an upper peripheral portion 456 opposite each other, the lower peripheral portion 454 having a reduced axial height along the centerline L1 relative to the upper peripheral portion 456 . The lower peripheral portion 454 and the upper 456 peripheral portion are connected to each other by two opposing lateral peripheral portions 458 .

The first cup 428 is symmetrical with respect to a plane passing through the centerline L1 of the injection portion 418 and passing through the reactant injector 436 ( FIG. 12 ).

A large opening 429 is formed in the wall of the first cup 428 between the hollow central region 450 and the upper peripheral portion 456 of the protruding peripheral region 452 . The opening 429 is inclined relative to the centerline L1 and a plane perpendicular to the centerline L1. The opening 429 has a substantially rounded triangular shape with one of its vertices located towards the injector 436 .

The first cup 428 has a peripheral edge 460 extending from the wall of the first cup 428 and extending generally perpendicular to the centerline L1. The peripheral edge 460 of the first cup 428 is fixed at the second cup 430 to seal the exhaust gas, for example by welding.

The second cup body 430 is disposed between the first cup body 428 and the downstream surface 22 .

Said second cup 430 is open towards the upstream face 20 and comprises an annular wall without sharp edges. The wall has a central area 462 protruding towards the upstream face 20 and a hollow peripheral area 464 surrounding said central area 462 towards the upstream face 20 . The hollow peripheral region 464 includes a lower peripheral portion 466 and an upper peripheral portion 468 opposite each other, the lower peripheral portion 466 having a reduced axial height along the centerline L1 relative to the upper peripheral portion 468 . The lower peripheral portion 466 and the upper peripheral portion 478 are connected to each other by two opposing lateral peripheral portions 470 .

The second cup 430 is symmetrical with respect to a plane passing through the centerline L1 of the injection portion 418 and passing through the reactant injector 436 ( FIG. 12 ).

An opening 472 is formed in the wall of the second cup 430 between the protruding central region 462 and the lower peripheral portion 466 of the hollow peripheral region 464 . The opening 472 is inclined relative to the centerline L1 and a plane perpendicular to the centerline L1. The opening 472 has a rounded crescent shape with a large side located opposite the injector 436 .

The opening 429 of the first cup 428 and the opening 472 of the second cup 430 are angularly offset from each other at an angle of substantially 180° about the center line L1.

According to an alternative, a second opening is provided in the wall of the first cup 428 between the hollow central area 450 and the lower peripheral portion 454 of the protruding peripheral area 452, opposite to said injector 436, substantially at said first The opening 472 of the second cup 430 is used to communicate with the opening 429, so that part of the gas can directly reach the opening 472 without passing through the flow channel, thereby reducing the back pressure.

The second cup 430 has a peripheral edge 474 extending from the wall of the second cup 430 and extending substantially perpendicular to the centerline L1. The peripheral edge 474 of the second cup 430 is fixed at the upstream housing 10 and the downstream housing 12 and the peripheral edge 460 of the first cup 428 to seal the exhaust gas, for example by welding.

When assembled, the two cups 428, 430 assume the shape of a "donut" and define between them two halves leading from the opening 429 of the first cup 428 to the opening 472 of the second cup 430. Ring pipe.

A reactant injector 436 is intended to be injected into the two semi-circular ducts defined by said two cups 428 , 430 , for which purpose it is mounted on the upper peripheral portion 456 of the peripheral region 452 of said first cup 428 , near the opening 429 . The injector 436 is oriented substantially at 45° relative to the center line L1 so that the jet is directed towards the convex central region 462 of said second cup 430 .

According to an alternative, the injector 436 is oriented so that the direction of injection is perpendicular to the two semi-circular ducts.

According to another alternative, said injector 436 is oriented so that the injection direction is parallel to the cut plane of said two semi-circular ducts, so that a more compact injection section 418 is obtained.

The operation of the exhaust duct according to the third embodiment described above will now be described in detail with reference to FIGS. 11 and 12 , in which the flow of exhaust gas is shown by arrows.

Exhaust gases reach the first cup 428 as previously described. The gas is collected by the first cup 428 after passing through the upstream block 14 .

The exhaust gas then passes through the flow channel via the opening 429 ( FIG. 11 ).

Urea is injected at the inlet of the flow channel and is converted to ammonia during the passage of the exhaust gas through the flow channel.

Due to the orientation of the injectors 436, the gas flow is distributed between the two semi-annular ducts.

A first portion of the gas flow flows upwardly to opening 472 using one of the semi-annular ducts along which it performs a helical motion about the centerline of the duct. The annular shape of the two cups 428, 430 imparts a rotational motion to this first portion of the airflow, making at least one complete revolution, or as many as four complete revolutions, about the centerline in a clockwise direction in FIG. 12 .

During this time, the second portion of the gas flow flows upwardly to opening 472 using another semi-circular duct along the duct in a helical motion about the duct centerline. The annular shape of the two cups 428, 430 imparts a rotational motion to this second portion of the airflow, making at least one complete revolution, or as many as four complete revolutions, about the centerline in a clockwise direction in FIG. 12 .

Once the gas passes through the opening 472 it will pass through the downstream block 16 .

Furthermore, as in the previous case, the mixer can be integrated into the flow channel and/or a part of the wall of the flow channel can comprise a wire mesh in order to guarantee an optimal homogeneity of the gas and urea and/or ammonia.

An advantage of this embodiment is that it allows good mixing of the gas and urea and/or ammonia.

The exhaust line according to the invention has the advantage that the distance between the two faces of the continuous block is reduced while leaving sufficient path length for the gas to guarantee the conversion of urea to ammonia. The length of this path is sufficient both to complete the chemical reaction that converts the urea injected into the exhaust into ammonia and to make the final exhaust/ammonia mixing as homogeneous as possible.

Claims (21)

1. an automobile exhaust pipeline (2) comprising:

(16) two blocks in upstream (14) and downstream, for the treatment of the waste gas that flows in described gas exhaust piping (2), this upstream (14) and downstream (16) block serial are arranged in the described gas exhaust piping (2);

Inject part (18; 318; 418), between the downstream face (22) that is arranged on the upstream face (20) that defined by described upstream block (14) and is defined by described downstream block (16), comprise: extend to the circulation passage (24) of described downstream face (22) for what waste gas stream arranged from described upstream face (20), this passage (24) is included in the center line (L1) that has definite length between described upstream face (20) and the described downstream face (22), described injection part (18; 318; 418) comprise and be installed in this injection part (18; 318; 418) go up and reactant can be injected into this injection reactant injection syringe (26 partly; 436);

It is characterized in that described injection part (18; 318; 418) comprise at least the first cup (30; 330; 430), this first cup is arranged in the described circulation passage (24) in the waste gas flow path, so that the average path of exhaust blast stream is than predetermined length height at least 20%;

Described injection part (18; 318; 418) comprise second cup (28; 328; 428), this second cup is arranged on described upstream face (20) and described first cup (30; 330; 430) in the described circulation passage (24) between;

Described reactant be infused in described first cup (30; 330; 430) and described second cup (28; 328; 428) finish between.

2. gas exhaust piping according to claim 1 is characterized in that, described definite length is between 40 to 140mm.

3. gas exhaust piping according to claim 1 is characterized in that, described first cup (30; 330) bottom centers on described injection part (18 with spirality; 318) center line (L1).

4. gas exhaust piping according to claim 3 is characterized in that, described first cup (30; 330) bottom centers on described injection part (18 with spirality; 318) center line (L1) carries out the rotation in 3/4ths weeks.

5. gas exhaust piping according to claim 3 is characterized in that, described first cup (30; 330) has opening (354) at the described upstream face of described spiral distance (20) place, end farthest.

6. according to each described gas exhaust piping of claim 3 to 5, it is characterized in that described first cup (330) has flow spoiler (380) at the described upstream face of described spiral distance (20) place, end farthest.

7. gas exhaust piping according to claim 6 is characterized in that, described flow spoiler (380) extends towards described upstream face (20) and described spiral outside from the bottom of described first cup (330).

8. gas exhaust piping according to claim 1 is characterized in that, described second cup (28; 328) center on described injection part (18 with spirality; The bottom of center line 318) (L1).

9. gas exhaust piping according to claim 8 is characterized in that, described second cup (28) has opening (29) at the described upstream face of described spiral distance (20) place, end farthest.

10. gas exhaust piping according to claim 8 is characterized in that, described second cup (328) has opening (329) at the place, end of described the most close spiral described upstream face (20).

11. to 10 each described gas exhaust pipings, it is characterized in that described first cup (30 according to Claim 8; 330) and described second cup (28; 328) defined spiral pipeline between the two at it, this spiral pipeline is from described second cup (28; 328) opening (29; 329) initial, lead to described first cup (30; 330) opening (354) stretches at least 180 °, and has greater than 2300mm ²Flat region.

12. gas exhaust piping according to claim 11 is characterized in that, described spiral pipeline is from described second cup (28; 328) opening (29; 329) initial, lead to described first cup (30; 330) opening (354) stretches 275 °, and has greater than 2300mm ²Flat region.

13. gas exhaust piping according to claim 1, it is characterized in that, described first cup (430) comprising: annular wall, this annular wall have towards the outstanding middle section (462) of described upstream face (20) with towards described upstream face (20), around the hollow outer peripheral areas (464) of described outstanding middle section (462); Opening (472), this opening (472) are formed on the wall of described outstanding middle section (462) and first cup (430) between the described hollow outer peripheral areas (464).

14. gas exhaust piping according to claim 13, it is characterized in that, described second cup (428) comprising: annular wall, this annular wall have towards the hollow central zone (450) of described upstream face (20) and outstanding towards described upstream face (20), around the outer peripheral areas (452) in described hollow central zone (450); Opening (429), this opening (429) are formed on the wall of second cup (428) between described hollow central zone (450) and the described outstanding outer peripheral areas (452).

15. gas exhaust piping according to claim 14, it is characterized in that the shape of described first and second cups (428,430) makes the opening (472) of waste gas from the opening (429) of described second cup (428) to described first cup (430) carry out spiral motion.

16., it is characterized in that described first cup (30 according to claim 9 or 10 described gas exhaust pipings; 330) have opening (354), described first cup (30 at the described upstream face of described spiral distance (20) place, end farthest; 330; 430) opening (354; 472) and described second cup (28; 328; 428) opening (29; 329; 429) setover at an angle to each other around described center line (L1).

17., it is characterized in that described first cup (30 according to claim 14 or 15 described gas exhaust pipings; 330; 430) opening (354; 472) and described second cup (28; 328; 428) opening (29; 329; 429) setover at an angle to each other around described center line (L1).

18. gas exhaust piping according to claim 1 is characterized in that, described cup (28; 328; 428) has the hole (40 that diameter equals 5mm substantially; 340) or have an opening.

19. gas exhaust piping according to claim 1 is characterized in that, described first cup (30; 330; 430) comprise silk screen layer (70) on its at least a portion surface.

20. gas exhaust piping according to claim 1 is characterized in that, described reactant injection syringe (26; 436) be oriented such that injection direction is perpendicular to described injection part (18; 318; 418).

21. gas exhaust piping according to claim 1 is characterized in that, described reactant injection syringe (26; 436) be oriented such that injection direction is parallel to described injection part (18; 318; 418) tangent plane.

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